PRAECIPUA (46 Leonis Minoris). While Leo
is easy to admire, its modern-constellation counterpart, faint Leo Minor, which rides the back of the
Zodiac's King of the Beasts, is not. Leo Minor, the "Lesser Lion,"
is so dim that few bother with him, and is so unimportant a
constellation that no one would think of making Leo into "Leo
Major," thus raising Leo Minor's rank. Because the modern
constellations were invented long after proper names were assigned,
most well after Bayer assigned Greek
letters (and to some degree were carved from other
constellations), the names of their stars can be a bit of a mess.
Only one star in Leo Minor carries a Greek letter name, and that is
"Beta;" there is no Alpha, and Beta Leonis Minoris is not even
brightest, coming in second. The little constellation does have
its charm however, mostly in a flat quadrilateral with the
constellation's luminary, bright fourth magnitude (3.83) 46 Leonis
at the eastern end (the "46" a Flamsteed number, the only
Flamsteed number whose star ranks "number 1" in a constellation).
Leo Minor is also one of the few modern constellation whose
brightest star carries a proper name, 46 Leo Minoris also called
"Praecipua," or "Chief," a "modern" term from Latin telling that
"46" is the brightest star. Praecipua is otherwise ordinary, an
orange class K (K0) giant-subgiant with a temperature of 4690
Kelvin. At a distance of 98 light years, it is not quite up to
average giant brightness, radiating 32 solar luminosities into
space, from which we derive a modest diameter (for a giant) 8.5
times that of the Sun. A star of around 1.5
solar masses, once a hydrogen-fusing cool class A star, it is now
evolved, and is quietly fusing helium to carbon in its core. The
star is known to be somewhat metal poor compared with the Sun, its
iron content down by about a third. Of most interest perhaps is
how well we know it. Recent accurate measures of angular diameter
by the Navy Interferometer show it to be 0.00254 seconds of arc
across (the separation of car headlights seen from a distance of
80,000 kilometers, 20 percent of the way to the Moon), which gives
it a physical diameter 8.2 times that of the Sun, the agreement
with the previously calculated diameter showing that we know the
size, temperature, luminosity, and distance very well.